This invention relates generally to improved processes and apparatus for positioning end turn insulation in stator assemblies made up of magnetic cores, two or more winding phases, and end turn insulation separating the end turn portions of different winding phases.
In the art, insulation which will be referred to herein as end turn insulation is also referred to as "phase insulation", "phase paper", "N-insulation", "ladder insulation", and "window insulation".
Historically, phase insulation has been manually positioned in slots of stator cores. This of course limits the productivity of motor manufacturers and contributes to higher costs for producing electric motors.
This problem has long been recognized in the art, and in addition to the solutions presented by the above-referenced related applications, others in the art have been attempting to develop still other solutions to the problem.
For example, as described in Lund U.S. Pat. No. 3,857,171 which issued Dec. 31, 1974; it is desirable to place insulation paper in the slots of magntic cores at substantially the same time that windings of the different winding phases are axially injected into the stator core slots. Clark U.S. Pat. No. 4,090,290 also recognizes the desirability of avoiding manual placement of individual insulators in the slots of magnetic cores. The approach suggested by Clark involves simultaneously transferring an end turn insulator and at least one winding coil from coil transfer tooling into the slots of stator cores. Some of the problems that have been encountered with the prior art approaches are also recognized, for example, in the United Kingdom Pat. No. 1,461,126 which was published Jan. 13, 1977 in the name of Droll.
The just-mentioned Lund, Clark and Droll patents all relate to the utilization of commonly available coil placing (i.e., coil injection) equipment. However, the illustration of such equipment is somewhat schematic in form in the above cited prior art. However, Walker et al. U.S. Pat. No. 3,402,462 which issued Sept. 24, 1968 contains rather good illustrations of coil placing equipment that is now well known in the art.
In attempting to follow the procedures taught in the prior art regarding machine placement of phase insulation by axially inserting the same with coil injection equipment, we have found that numerous other problems arise which prevent the utilization of such processes. Moreover, many of the problems remain whether conventional phase insulation stamped from flat sheet material is utilized or phase insulation is utilized as illustrated for example in the above-referenced Droll patent wherein the phase insulation is fabricated from filamentary material and flat strip material.
More specifically, as we have attempted to axially place phase insulation with coil injection equipment into the axially extending slots of stators (having bores in the neighborhood of five to five and one-half inches, and stack heights in the neighborhood of, for example, five to eight inches) the phase insulation would either be torn apart and destroyed or so severely mispositioned that more operator time was required to satisfactorily reposition the phase insulation than would have been required to manually place the phase insulation in the first instance.
Thus it should now be appreciated that it would be desirable to provide new and improved processes and apparatus for axially injecting phase insulation having legs that extend axially along axially extending slots of a dynamoelectric machine stator such that the phase insulation is neither so badly damaged as to be unusable, nor is so badly misplaced that any time savings associated with machine placement of the insulation is more than offset by the time consumed in manually repositioning mispositioned phase insulation.
Accordingly, it is a general object of the present invention to provide new and improved apparatus and methods for axially positioning leg portions of phase insulation in axially extending slots of stator cores by transferring such phase insulation from coil injection equipment into such slots in conjunction with operation of coil injection tooling being utilized for axially placing winding turns into the stator core slots.
It is another object of the present invention to provide new and improved apparatus and methods which fulfill the just-mentioned object and yet which may be carried into practice with conventional phase insulation having flat legs as well as phase insulation having filamentary type interconnecting legs.
It is still another object of the present invention to provide new and improved methods and apparatus for axially inserting phase insulation into a stator core in conjunction with a conventional coil placing procedure.